January 29th, 2016 Release.
In addition to bug fixes there are some notable features for the Android support in this new release of Android Studio IDE. Android Studio offers:

In this release, we've completely turned off in-memory dexing by default. We've spent the last couple of previews trying to fine-tune it, but there are lingering issues which continues to affect users.

This should hopefully make the builds work a lot better for many of you. (If things were already working well, you can continue with in-memory dexing by turning it on with android.dexOptions.dexInProcess=true.)

We've also continued to fix various Instant Run scenarios; in particular, using APK splits on API 23 seems to trigger some platform bugs, so for now we've switched over to using multidex for coldswap for both Lollipop and Marshmallow.

October 12th, 2015 Release.
In addition to bug fixes there are some notable features for the Android support in this new release of Android Studio IDE. Android Studio offers:

The memory profiler has a new "analysis" feature where it can analyze a heap dump to look for known problems, such as leaked activities. To use this feature, open a heap dump and look for the Analyzer Tasks window on the right.

In the analysis window you can press the Run button to perform and analysis, and then drill into the results; here's an example of a leaked activity.

There are several new lint checks as well; here's one which warns you if you are attempting to override resources referenced from the manifest (where only a small set of resources are actually dynamically resolved).

Overall there are a number of bug fixes, particularly in the editing area where we're working to polish code completion in resource and manifest files. For example, you can use short names in completion to custom views now.

Android Studio is a new Android development environment based on IntelliJ IDEA. Similar to Eclipse with the ADT Plugin, Android Studio provides integrated Android developer tools for development and debugging. Android Studio offers:

Gradle-based build support.

Android-specific refactoring and quick fixes.

Lint tools to catch performance, usability, version compatibility and other problems.

ProGuard and app-signing capabilities.

Template-based wizards to create common Android designs and components.

A rich layout editor that allows you to drag-and-drop UI components, preview layouts on multiple screen configurations, and much more.